Hammered metal finish



Patented Mar. 21, 1939 HAMMERED METAL FINISH Guido Ariotti, Stamford, Conn., assignor to Atlas Powder Company, Wilmington, DeL, a corporation of Delaware No Drawing; Application March 26, 1937,

Serial No. 133,184

10 Claims.

This invention relates to a new method of finishing surfaces in simulation of hammered metal and to a composition for use in producing such finishes.

In the decoration of metallic surfaces, it has in the past been conventional to produce a hammered eflect thereon by hammering the entire exposed surface of the metal with a round headed hammer or by means of a suitable machine producing the same effect. The effect produced is well known and comprises innumerable I depressed portions over the surface of the metal.

This method is tedious and expensive. Moreover, it can be produced only on metal surfaces and preferably those which are of softmetal. The metal base must be of substantial thickness in order to withstand the hammering and to yield the desired effect. Consequently, it is de-,

sirable to have available a. simple method by which there may be applied to any base a coating material which will, when d y, yield a surface which simulates hammered metal in appearance.

This invention has for its principal object the provision of a coating composition which, when applied to a suitable base material, will dry to a protective coating which simulates hammered metal in appearance.

Another object of this invention is to provide a coating technique which enables the production of a hammered metal finish by a one-coat application. This enables the rapid production of the finish and reduces the expense thereof to a considerable extent.

Other objects of this invention-will more fully hereinafter appear.

This invention contemplates a method of .application of the coating material by what is known as a one-coat practice. In this specification, the expression one-coat means that the coating composition is applied in one coat only and that no portion of the surface is gone over after the first coating on that portion has dried. As will presently appear, the term "one-coa includes a method wherein the entire surface is gone overonce and then, before any portion has dried, i. e.

before the volatile solvent has had an opportunity to evaporate,.the entire surface is gone over again so quickly that no portion of the first coat is allowed to dry or the volatile solvent contained therein allowed to evaporate before the second-coat is applied to that portion. The term "one-coat also includes a method wherein the entire surface is gone over only once. This meaning of the term "one-coa is a matter of common knowledge to those versedin coating methods.

the type which is baked.

I have discovered that by the application to a surface to be coated of a composition of matter comprising a synthetic or natural resinous base or varnish, metal powder and a thinner more fully described below, in such proportions as to form a sprayable coating composition by means of a spraying device so adjusted as to produce a spattering action, that a hammered metal finish is obtained by one coat.

As the base material to be provided with the hammered metal finish, I prefer to use any smooth, relatively hard surface such as metal, metal foil, regenerated cellulose sheets, wood, wood already lacquered or otherwise coated with a smooth, hard surface of enamel, varnish or the like, glass, ceramic ware, etc. However, I may apply my finishing material to fibrous materials such as cloth, woven fabrics, paper, and the like, after they have been provided with a smooth, hard surface of lacquer, or the like, which is not softened or dissolved excessively by the ingradients of 'my composition.

As the binder or base for my composition, I may use any natural or synthetic resinous base such as a resin-oil varnish or the like. I may use either a natural or synthetic resin itself or I may use it dissolved in a drying oil to form a. varnish base. As examples of suitable resins contemplated by this invention, I may enumerate phenolformaldehyde or polybasic acid-polyhydric alcohol resins either unmodified or modified by numerous materialsknown in the art. These modifiers might include drying oils, drying oil fatty acids, non-drying oils, non-drying oil fatty acids, rosin, natural resins, such as copals, or

such a resin as shellac. Any of the modified alkyd resins may have an additional-phenol modificatio'nor treatment. Alternatively, I may use as a base cumarone-indene' resin, reacted or cooked with a drying oil such as linseed oil. 40

Similarly, other resins such as the phenolaldehyde resins, copal's, and other natural resins, may be cooked with an oil to produce a suitable base. The base may be either air-drying or of 4 1) The base material may be either pigmented or unpigmented, as desired. In order, however, to produce a finish simulating more closely a genuine hammered metal finish, I find it highly desirable to have the base material pigmented p by grinding it with a pigment designed to give an appropriate tint to the resulting finish. Thus, in the preferred practice of the invention, I use a black pigment in conjunction with aluminum bronze as the metallic powder whereby a black hammered metal finish is obtained; Similarly, in producing a hammered copper finish I use a brown or pink pigment in conjunction with copper powder. In place of using a pigment to obtain 5 the desired color in the finish, I may use dyestuffs soluble in the coating composition. These and other modifications will be obvious to those skilled in the art. I may add the pigment or dye to the composition at any stage in its preparation, but I prefer to have it previously incorporated in the base material by grinding to form a synthetic enamel. I may ship the composition in three containers, the pigmented base or vehicle in one, the aluminum bronze in anbother and the unique thinner to be described below in the third, leaving it to the user to add the desired quantities of metallic powder (aluminum bronze) and thinner to the base.,immediately before use, or I may blend the complete composition together in the correct proportions and ship the finished product ready for application.

. As the metal powder, I prefer to use aluminum powder in the form known to the art as aluminum bronze. This is not a granular material,

but consists of flakes. It is produced by a hammering process rather than by grinding. However, one may use copper, brass, bronze, gold or any other decorative, flake, metallic powder, a1-

though aluminum powder produces the best resuits because it tends to float readily on account of its low specific gravity, and because its color produces a closer simulation of a hammered metal effect than do the. other powders enumerated.-

The finer this powder is the better results I am able to obtain. The powder must in any event be of such a fineness that it will have a tendency to float to the surface of the applied wet film. Stearic acid is commonly used as a lubricant in 40 the production of metallic powder in the form of flakes, and is commonly present in small quantitles in the commercial product. I have found that its presence is desirable. In some cases, I may add small amounts of stearic acid to my 46 composition since it exerts a peculiar action upon the metal powder, increasing its floating tendency and improving the finish andproducing reater uniformity of the hammered metal eflect. The thinner referred to above is composed of 50 two miscible solventsof radically different volatilities, one of which is slowly volatile, known in theart as a high boiler, andthe other of which is highly volatile, knownin the art as a low boiler. As a preferred thinner, I use a mixture consisting of hydrogenated petroleum naphtha and denatured ethyl alcohol in the proportions of 3 3% of hydrogenated petroleum naphtha such-as Solvesso #3, having a flash point of 135 F. and boiling point range of 365-419 F., and 67% of r denatured ethyl alcohol, having a flash point of 5l.8 F. and a boiling point of about 172 F. As the denatured ethyl alcohol, I use an alcohol containing no undesirable denaturants which might spoil the finish and prefer to use specially denatured ethyl alcohol known as formula #1 'which is denatured with about 5% of methyl alcohol, methyl alcohol being even more volatile than ethyl alcohol. The thinner contains the highly volatile solvent and the slowly volatile solvent in such proportions that if a plate of any 1 smooth, hard material such as metal iscoated. with a thin film of the thinner alone and allowed to dry, the highly volatile solvent, in this case ethyl alcohol, will evaporate almost at once from the surface while the slowly volatile solvent,

namely the hydrogenated petroleum naphtha, will remain and will form into small individual droplets. The action of the thinner in the coating composition is to float the aluminum powder to the edge of these droplets as they are formed, giving rise to a great number of small circles and to the non-uniform efiect known as a hammered metal finish.

It will be obvious that a thinner consisting of other solvents than those Just described may be used, if desired. :Il may use any mixture of a slowly volatile solvent and a highly volatile solvent, which mixture will dissolve the resinous base material and form a suitable coating composition. The' following solvent combinations may be used to produce variations in the hammered metal effect. Thus, in place of Solvesso No. 3, in conjunction with alcohol, I may use the same percentages of Solvesso No. 2 (boiling point range 275-365 F.) high flash petroleum naphtha, xylol, toluol, Solvesso No. 1 (boiling point range 200-275" F.) and similar slowly volatile solvents. In place of ethyl alcohol, I may use similar proportions of acetone, methyl alcohol, and similar highly volatile solvents. In general, the two. solvents selected must be such that their boiling points have a difference of at least approximately 30 F. or more. Instead of using a single highly volatile solvent or a single slowly volatile solvent, I may use two or'more solvents in each class. Where the claims specify a solvent", such a mixture of two or more solvents, as well as a single solvent, is contemplated.

The thinner above described is added to the resinous base or vehicle at least in sufficient quantity to bring the same into solution, and preferably in considerable excess of this quantity for sprayability and so that greater opportunity is afiorded for rapid evaporation of the highly volatile solvent by reason of the thus obtained lower proportion of total solids in the-coating composition. The metal powder is added to the base either before or after the addition of the thinner. The mixture isshaken well, whereupon the metal powder is fioated", suspended or dis tributed throughout the solution. The coating composition is now ready for application.

A suitable quantity of the coating composition is placed into a pressure feed gun equipped with a spatt'ering cap forlthe spray nozzle. However, any spray gun which will spatter is satisfactory. The method of application is such that-the coating composition, by reason of the structure of the spraying device, is formed into relatively large individualdroplets which are thrown ,onto the surface without substantial evaporation of any portion of the solvent contained therein during their projection from the spraying nozzle to the surface being coated. The pressure feed gun is connected with a source of air under pressure and is placed in operation at a suitable distance from the article to be finished which is gone over completely. The wet coated article es very rapidly, forming the hammered metalefl'ect al-'- most-immediately. It is then permitted to dry until hard or is baked if necessary to give it sufficient hardness.

For greater -depth and thickness and for; greater speed and uniformity, instead of employing the technique just described, I may first apply a mist of the coating composition just described over the entire surface of the work im- The fine drops from the. mist form a uniform coating over the entire surface which acts as a background for the spatter coat which is applied thereover. By a mist'QI refer to a fine spray obtained by adjustment of the spray gun in the correct manner.

As an example of a preferred coating composition contemplated by the present invention, I give the following:

A pigmented resinous base material is first prepared as fol'lows:

- The following ingredients in the following proportions are used- Percent by weight Linseed oil 30 Glycerine 35 Phthalic anhydride 35 Equal parts by weight of phthalic anhydride and. glycerine are. added into the kettle.' This isheated slowly up' to about 200, at which point about half of the linseed oil is added. The mixture is heated very slowlyup to 325 F. at which point the reaction, depending on the linseed oil composition, begins. The batch may be made up in an inert atmosphere (such as carbon dioxide or nitrogen) and with or without mechanical agitation, but agitation is preferred. At 400 F. the remainder of the linseed oil is added and the temperature-is increased to 425 F., and held at this point until the reaction ceases. Then the temperature is raised to 450 or 460 F. until the right viscosity is obtained. The resin is then removed into a cooling kettle and-allowed to cool.

' lated by the color of the pigment, and its physical properties.-

Any given quantity of the above described black, pigmented, resinous base material is taken. An equal volume of thinner composed of 33% by volume of hydrogenated petroleum naphtha in the form known as Solvesso No. 3 and 67% of denatured ethyl alcohol, known as S. D. No. 1, is addedto the pigmented resinous base material. The materials are agitated until a homogeneous solution is obtained. 4 ounces of finely divided aluminum bronze powder are added to each gallon of the mixture. The solution 'or coating composition thus obtained produces, when spattered onto a smooth, hard, surface in the manner described above, a hammered metal finish having a marked resemblance to genuine hammered metal.

In the foregoing example, I am not limited as to the amount of bronze powder. It might run as low as to 1 ounce per gallon or might be as much as 10 to ounces per gallon, depending on ,the results which are desired.

It will be seen that I have devised a newcoating composition and process of applying same of great usefulness in the art of finishing materials.- It is to be understood that I do not wish to be limited to the specific description above but that this invention is to be limited only as set forth in the appended claims.

Having described. my invention, claim is: v

1. A coating composition adapted to what I produce a hammered metal finish, said compositioncomprising a finely divided metal powder, a. filmforming constituent consisting essentially ofa material selected from the group consisting of synthetic and natural resins and synthetic and natural resin varnishes, and a solvent for the film-forming constituent in sufiicient proportion to yield a fluid, readily sprayable mixture, said solvent consisting of a slowly volatile, hydrogenat'ed petroleumnaphtha and a material selected from the group consisting of methyl alcohol, ethyl alcohol and acetone.

2. A coating composition adapted to produce a hammered metal finish which comprises a resinous base, a finely divided metal powder, and a solvent for the resinous base consisting of 33% of hydrogenated petroleum naphtha having a flash point of'about 135 F., and a boiling point range of about 365-419 F., and of 67% of denatured ethyl'alcohol having a flash point of about 51.8 F. and a boiling point of about 172 F. 3. A coating composition adapted to produce a hammered metal finish which comprises a mixture of equal volumes of a black, pigmented, synthetic resinous base and of a solvent for the same consisting of 33% of hydrogenated petroleum naphtha having a flash point of about 135 F. and a boiling point range of about 365-419 F., and of 67% of denatured ethyl alcohol having a flash point of about 51.8 F. and a boiling point of about 172- F., and aluminum bronze powder in the proportion of 4 ounces per gallon of said mixture.

4. A process of providing a base material with a finish simulating hammered metal which comprises applying thereto by a spattering operation a coating composition comprising a finely divided metal powder, a film-forming constitutent consisting essentially of a material selected from the group consisting of synthetic and natural resins and synthetic and natural resin varnishes, and a solvent for the film-forming constitutent in willcient proportion to yield a fluid, readily sprayable mixture, said solvent consisting of a slowly vola tile hydrogenated petroleum naphtha and a material selected from the group consisting of methyl alcohol, ethyl alcohol and acetone.

5. A process of providing a base material with a finishz' simulating hammered metal which comprises applying thereto by a spattering operation a coating composition comprising a resinous base, a finely divided metal powder, and a solvent for the resinous base'consisting' of 33% of hydrogenated petroleum naphtha having a flash point of about 135 Rand a boiling point range' of about 365-419 F., and of 67% of denatured ethyl alcohol having a fiash point of about 51.8 1i. and a boiling point of about 172 F.

6. A process of providing asmooth, non-porous base material with a finish simulating hammered metal which comprises applying ther to by a spattering operation a coating composition comprising a mixture of equal volumes of a black pigmented synthetic resinous base and of a solvent for the same consisting of 33% of hydrogenated petroleum naphtha having a flash point of about 135 F. and a boiling point range of about 365-419 F., and of 67% of denatured ethyl alcohol having a flash point of about 51.8 F. and a boiling point of about 172 F. and aluminum bronze powder in the proportion of 4 ounces per.

gallon of sa.id mixture.

7. A process of providing a metal surface with a finish simulating hammered metal which comprises applylng thereto a mist of a coating com-' from the group consisting of methyl pigment, finely divided aluminum powder and a solvent for the resinous base consisting of denatured ethyl alcohol and a slowly volatile hydrogenated petroleum naphtha, and then applying to said metal surface by a spattering operation the same material.

8. An article of manufacture comprising a smooth non-porous base material provided with a spattered surface film of a finishing material simulating hammered metal, said finishing material comprising the residue of a composition comprising a finely divided metal powder, afilmforming constituent consisting essentially of a material selected from the group consisting of synthetic and natural resins and synthetic and natural resin varnishes. and a solvent for the film-forming constituent in suificient proportion to yield a fluid, readily sprayable mixture, said solvent consisting of a slowly volatile hydrogenated petroleum naphtha and a material selected alcohol, ethyl alcohol and acetone.

9. An article of manufacture comprising a smooth, non-porous base material provided with a surface film of a finishing material simulating hammered metal, said finishing material comprising the residue of a composition comprising a resinous base, finely divided aluminum powder and a solvent for the resinous base in ,sufilcient proportion to yield a fluid readily sprayable mixture, said solvent consisting of 33% of hydrogenated petroleum naphtha having a flash point of about 135 F. and a boiling point range oi about 365-419 F., and of 67% oi. denatured ethyl alcohol having a fiash point of "about 51.8.F. and a boiling point of about 172 F.

.10. A process or providing a base material with a finish simulating hammered metal which comprises applying thereto a mist of a coating composition comprising a finely divided metal powder, a film-forming constituent consisting essentially of a material selected from the group consisting oi synthetic and natural resins and.

synthetic and natural resin varnishes, and a solvent for the film-forming constituent in willcient proportion to yield'a fluid, readily sprayable mixture, said solvent consisting of a slowly volatile hydrogenated petroleum naphtha and a material selected from the group consisting of. methyl alcohol, ethyl alcohol and acetone, and then applying to the mist-coated surface by a spattering operation the same material.

GUIDO ARIO'I'I'I. 

